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Biomedical subjects

P C Doherty

Publications and source records attributed to P C Doherty.

At least 19 recordsLinked to original sources
PubMed1992

Delayed clearance of Sendai virus in mice lacking class I MHC-restricted CD8+ T cells.

The role and interdependence of CD8+ and CD4+ alpha beta-T cells in the acute response after respiratory infection with the murine parainfluenza type 1 virus, Sendai virus, has been analyzed for H-2b mice. Enrichment of CD8+ virus-specific CTL effectors in the lungs of immunologically intact C57BL/6 animals coincided with the clearance of the virus from this site by day 10 after infection. Removal of the CD4+ T cells by in vivo mAb treatment did not affect appreciably either the recruitment of CD8+ T cells to the infected lung, or their development into virus-specific cytotoxic effectors. In contrast, depletion of the CD8+ subset delayed virus clearance, although most mice survived the infection. Transgenic H-2b F3 mice homozygous (-/-) for a beta 2 microglobulin (beta 2-m) gene disruption, which lack both class I MHC glycoproteins and mature CD8+ alpha beta-T cells, showed a comparable, delayed clearance of Sendai virus from the lung. Virus-specific, class II MHC-restricted CTL were demonstrated in both freshly isolated bronchoalveolar lavage populations and cultured lymph node and spleen tissue from the beta 2-m (-/-) transgenics. Treatment of the beta 2-m (-/-) mice with the mAb to CD4 led to delayed virus clearance and death, which was also the case for normal mice that were depleted simultaneously of the CD4+ and CD8+ subsets. These results indicate that, although classical class I MHC-restricted CD8+ cytotoxic T cells normally play a dominant role in the recovery of mice acutely infected with Sendai virus, alternative mechanisms involving CD4+ T cells exist and can compensate, in time, for the loss of CD8+ T cell function.

Animals↗
PubMed1992

Analyzing the distribution of cells expressing mRNA for T cell receptor gamma and delta chains in a virus-induced inflammatory process.

Acute inflammatory processes are extremely complex, containing sets of activated cells that may be difficult to categorize. The interface between two methodologies for characterizing the involvement of gamma delta T cells, in situ hybridization to detect T cell receptor (TCR) mRNA and flow cytometric analysis of surface TCR expression, is utilized here to study the pneumonia caused by intranasal (i.n.) infection of mice with influenza A viruses. Substantial numbers of cells expressing mRNA for the gamma and delta TCR chains are present in bronchoalveolar lavage (BAL) populations obtained either late in the course of primary infection with an H3N2 virus or within a few days of secondary challenge with an H1N1 virus. The majority of the gamma delta TCR mRNA+ cells detected in FACS-separated BAL populations partition to the Thy1+ gamma delta TCR+ subset, while relatively few (less than 10%) C delta mRNA transcripts are found in cells that phagocytose latex particles. However, an additional set of gamma delta TCR mRNA+ cells is also located in a high side scatter (H-SSC) population, which stains nonspecifically with monoclonal antibodies (mAbs) and is normally gated out in the process of flow cytometric analysis. This H-SSC population tends to be enriched for cells expressing C gamma 1/2 rather than C gamma 4 mRNA. While some gamma delta TCR+ lymphocytes can be demonstrated by in vitro stimulation of the CD3 epsilon+ subset within this H-SSC population, the majority of the gamma delta T cell precursors that can be expanded in culture demonstrate a low side scatter (L-SSC) profile more characteristic of normal T lymphocytes. The possibility that subsets of activated, granular (H-SSC) alpha beta TCR+ and C gamma 1/2 mRNA+ gamma delta T cells are being missed when conventional FACS analysis is used to study this viral pneumonia is discussed.

Animals↗
PubMed1992

Extent of gamma delta T cell involvement in the pneumonia caused by Sendai virus.

The prevalence of gamma delta T cells in bronchoalveolar lavage (BAL) populations recovered from the respiratory tract of young, adult C57BL/6J mice infected intranasally (i.n.) with Sendai virus has been assessed by FACS-phenotyping, and by probing cytocentrifuge preparations for expression of TCR gamma mRNA. The surface gamma delta TCR+ set comprised from 5 to 20% of the inflammatory lymphocytes in sequential samples taken throughout the course of this nonfatal viral pneumonia. The BAL population also contained numerous cells expressing mRNA for C gamma 1/2 and C gamma 4; the C-regions were utilized for productive TCR gene rearrangement. Sorting the lymphocytes from the BAL established that greater than 90% of both the TCR gamma and TCR beta mRNA partitioned to cells with the appropriate surface TCR phenotype, while less than 7% of the TCR mRNA+ cells in the total inflammatory exudate were phagocytes that engulfed latex particles. Both the frequency and the total numbers of the gamma delta TCR+ and TCR gamma mRNA+ cells were increased in mice depleted of alpha beta T cells by in vivo treatment with mAbs to CD4 and CD8, indicating that the CD4+ and CD8+ alpha beta and CD4-8- gamma delta T cell subsets may operate independently in this virus disease. The C gamma 1/2 mRNA phenotype predominated throughout the course of the active infection, with a transition to maximal prevalence of the C gamma 4 mRNA+ set occurring very late (Day 20) in the resolving inflammatory process. Large numbers of macrophages expressing mRNA (greater than 50%) for a mammalian 65-kDa heat shock protein (hsp65), a possible target for some of the gamma delta T cells, were present early (Days 5-7) and remained at lower levels (less than 20%) thereafter. These hsp65 mRNA+ macrophages were much less apparent in BAL populations from mice depleted concurrently of the CD4+ and CD8+ T cell subsets, indicating that exposure to Sendai virus alone is not the major factor inducing the transcription of this endogenous gene. These experiments thus establish that gamma delta T cells are a minority of the infiltrating lymphocytes in Sendai virus pneumonia and provide new insights into the spectrum of hsp65 mRNA and TCR gamma mRNA expression during an inflammatory process.

Animals↗
PubMed1992

Roles of alpha beta and gamma delta T cell subsets in viral immunity.

The current status of T-cell subset involvement in viral immunity is summarized for experimental studies in mice. The immunobiology of the normal host response is discussed, with particular reference to lymphocytic choriomeningitis (LCM) and influenza. The general impression is that CD8+ cytotoxic T lymphocytes, CD4+ TH1 cells, gamma interferon, and IL-2 are of major importance, with these different components of the immune system interacting to promote an optimal response. However, experiments with a variety of virus systems indicate that there is considerable plasticity, at least in young, adult mice. Other mechanisms often compensate if a key lymphocyte subset is absent throughout the development of the immune response. Influenza-infected mice depleted of either CD4+ or CD8+ T cells clear virus and recover, though the latter may not be true for the elimination of LCM virus. Emerging information on the involvement of gamma delta T cells in viral pneumonia is summarized, but there is as yet no understanding of the biological significance (if any) of these lymphocytes in viral immunity. The point is made that alpha beta T-cell memory to viruses is long-lived, and the need for antigen persistence to maintain such memory is questioned.

Animals↗
PubMed1991

Clearance of influenza virus respiratory infection in mice lacking class I major histocompatibility complex-restricted CD8+ T cells.

Transgenic mice homozygous for a beta 2-microglobulin (beta 2-m) gene disruption and normal mice that had been treated with a CD8-specific mAb were infected intranasally with an H3N2 influenza A virus. Both groups of CD8T cell-deficient mice eliminated the virus from the infected respiratory tract. Potent CTL activity was detected in lung lavage populations taken from mice with intact CD8+ T cell function, with minimal levels of cytotoxicity being found for inflammatory cells obtained from the antibody-treated and beta 2-m mutant mice. We therefore conclude that cells infected with an influenza A virus can be cleared from the respiratory tract of mice lacking both functional class I major histocompatibility complex (MHC) glycoproteins and class I MHC-restricted, CD8+ effector T cells.

Animals↗
PubMed1991

Activation status of the CD4-8- gamma delta-T cells recovered from mice with influenza pneumonia.

The role that gamma delta-T lymphocytes play in virus infections is yet to be defined. The TCR-gamma delta + cell population found late in the course of influenza pneumonia has been analyzed for ligand-dependent lytic function. These gamma delta-T cells are not constitutively cytotoxic when recovered directly from the site of virus-induced damage in the respiratory tract, although the TCR-alpha beta + population that is present concurrently contains such lytic effectors. Both sets of lymphocytes mediate cytotoxic activity after further in vitro stimulation in the presence of mAb to CD3 and low concentrations of rIL-2. Secondary stimulation in vivo with a cross-reactive influenza A virus does not lead to the emergence of a cytotoxic gamma delta-T cell population, although substantial numbers of these gamma delta-T cells express mRNA for a variety of lymphokines and cytokines. Analysis of DNA content indicates that many of the gamma delta-T cells isolated directly from the pneumonic lung are cycling. This could reflect continuing stimulation by a specific ligand, perhaps a self-component expressed at abnormally high levels in the site of virus-induced pathology. However, we could find no evidence to indicate that the gamma delta-T cells are acting to eliminate redundant components of the host response. The percentage of inflammatory macrophages and nonphagocytic cells expressing mRNA for a 65-kDa heat-shock protein (the proposed target for at least a subset of these gamma delta-T cells) is not reduced during the time that lymphocytes with mRNA for the TCR-gamma delta are present in greatest numbers. Possible alternative functions for the gamma delta-T cells are discussed.

Animals↗
PubMed1991

Size and frequency characteristics of alpha beta and gamma delta T cells in the spleens of normal and cyclophosphamide-suppressed virus-infected chickens.

The characteristics of avian lymphocytes expressing surface CD8 (CT8) and T cell receptor (TCR) glycoproteins have been monitored by two-color flow microfluorimetry. Exposure of 1-month-old birds to a lethal influenza A virus, which is known to be lympholytic, significantly decreased the frequency of both the alpha beta TCR2+CT8+ and gamma delta TCR1+CT8- subsets in spleen. However, all categories of T cells showed evidence of greater mean cell size, indicating that they are responding. Inoculation of baby chicks with fowl pox virus induced a response more typical of specific immunity in the TCR2+CT8+ set, in that the lymphocytes increased in both frequency and mean cell size. Greater numbers of lymphoblasts were also found for the TCR2+CT8-, TCR1+CT8+, and TCR1+CT8- subsets, but the total cell counts for the minority TCR1+CT8- cells in spleen were consistently decreased. Immunosuppression with cyclophosphamide prior to infection eliminated 90% of the white blood cells from spleen, with the greatest effect being on the TCR1+ populations. The CT8+ alpha beta T cell response in chick spleen following exposure to a poxvirus is thus comparable to the situation observed for this subset of lymphocytes in mice infected with other viruses. However, although the gamma delta T cells increase in size, their frequency in spleen either does not change (CT8+) or is significantly decreased (CT8-).

Animals↗
PubMed1991

Lack of an inhibitory effect of hyperprolactinemia on androgen-dependent marking.

An experiment was performed to determine if hyperprolactinemia (chronically elevated serum prolactin levels), which inhibits testosterone-activated male sexual activity, also affects other androgen-dependent behaviors. Thus defecation and urine marking in response to a novel environment were examined in sham-operated and pituitary-grafted (hyperprolactinemic) male rats that had been castrated or castrated and given subcutaneous testosterone implants. Both castration and pituitary grafting significantly inhibited defecation, with the inhibitory effects of hyperprolactinemia being most pronounced in the castrated non-testosterone-treated animals. In contrast, castration significantly reduced the amount of urine marking observed, but pituitary grafting was without effect on this behavior. Thus, although hyperprolactinemia may inhibit sexual activity through an antagonism of the activational effects of testosterone, these results suggest that this effect is specific to sexual behavior and does not involve a more generalized inhibition of the effects of testosterone on androgen-dependent behaviors.

Animals↗
PubMed1991

Influenza virus RNA in the lung and lymphoid tissue of immunologically intact and CD4-depleted mice.

The distribution and clearance of viral RNA (vRNA) and mRNA has been analysed for the acute and recovery stages of the pneumonia induced by intranasal infection of C57BL/6J mice with H3N2 influenza A viruses. Amplification of viral genomic material by the polymerase chain reaction showed that the influenza haemagglutinin (HA) gene was eliminated from the lungs of immunologically intact mice by day 14 post-infection, whereas in vitro depletion of the CD4+ T cells delayed clearance by at most 4 days. Viral RNA encoding the HA gene was first demonstrated in the regional mediastinal lymph nodes at 48 h, and continued to be present until day 6 or day 10 after infection of the intact and CD4-depleted mice, respectively. Evidence for the presence of vRNA in the thymus, but not in the mesenteric lymph nodes or the spleen, was found in some situations. Otherwise, the distribution and clearance of vRNA was as would be predicted from earlier studies using virus isolation procedures to monitor localization patterns, and shows a lack of long-term persistence of the influenza virus genome.

Acute Disease↗
PubMed1991

Preferential increase in pituitary prolactin versus vasoactive intestinal peptide as a function of estradiol benzoate dose in the ovariectomized rat.

Vasoactive intestinal peptide (VIP) is synthesized in various tissues, including the anterior pituitary gland, where it may stimulate the release of PRL. Because estrogen plays a central role in the regulation of PRL, it becomes important to determine the effects of this steroid on both pituitary VIP and PRL. To study this, pituitary VIP and PRL and plasma PRL were assayed in ovariectomized rats after treatment with estradiol benzoate (EB; 0.007, 0.07, 0.7, 7 or 70 microgram/rat). Pituitary and plasma TSH were also determined as well as VIP content in the medial basal hypothalamus, suprachiasmatic region, cerebral cortex, and jejunum. Oil-treated rats served as controls. Injection of 0.7 or 7 microgram EB resulted in a significant increase in pituitary PRL without changing plasma PRL levels or pituitary VIP content compared to values in the control group. Only treatment with 70 microgram EB produced a significant increase in both pituitary VIP and PRL as well as in plasma PRL compared to control values. EB treatment at any of the doses used had no significant effect on pituitary and plasma TSH or VIP content in any of the other tissues examined. These data show that pituitary PRL and VIP are differentially regulated in response to estrogen. The increases in pituitary VIP and basal plasma PRL after treatment with the highest dose of EB suggest that pituitary VIP may be involved in the development of estrogen-induced hyperprolactinemia. These data also show that the regulations of pituitary VIP and TSH are independent of each other in the estrogen-treated rat.

Animals↗
PubMed1990

Late dominance of the inflammatory process in murine influenza by gamma/delta + T cells.

The inflammatory response in the lungs of mice infected with an influenza A virus consists largely of macrophages and CD3+ T cells. Most T lymphocytes recovered before day 7 after infection express mRNA for the T cell receptor alpha/beta (TCR-alpha/beta), while TCR-gamma/delta mRNA+ cells are found at much higher frequency over the next 7 d. The predominant surface phenotype for the TCR-gamma/delta mRNA+ population is CD3+4-8-TCR-alpha/beta-. Some lymphocytes expressing all the known V gamma genes are found in the inflammatory exudate, but V gamma 2+/V gamma 1+ and V gamma 4+ T cells are present at highest frequency. The response is staged, with maximal numbers of V gamma 4+ cells occurring on day 10 after infection, while the predominant phenotype on day 13 is V gamma 2/V gamma 1+. The emerging peak in numbers of V gamma 4+ lymphocytes is paralleled by increasing numbers of macrophages expressing hsp mRNA. The later maxima found for the V gamma 2+/V gamma 1+ T cells is consistent with the possibility that at least some of these lymphocytes are responding to the hsp+ cells and are functioning to resolve the inflammatory process.

Animals↗
PubMed1990

Cellular events in the lymph node and lung of mice with influenza. Consequences of depleting CD4+ T cells.

The cellularity of the mediastinal lymph nodes of mice infected intranasally with a high dose of an H3N2 influenza A virus increases massively within 5 days. All classes of lymphocytes are involved. A similar, but much smaller, expansion in cell numbers occurs after exposure to a comparable dilution of normal chick allantoic fluid. In the control group, this increase in lymph node size is totally prevented by the in vivo depletion of CD4+ T cells whereas there is only a 50% reduction in the virus-infected mice. The lymphocyte component of the cellular exudate in the lungs of infected mice is dominated by activated, CD8+ T cells, which are also prevalent in the mediastinal lymph nodes. Elimination of the CD4+ subset does not greatly diminish the severity of this inflammatory process. The CD4-depleted mice clear the virus from the lung, and there is little effect on the frequency of virus-specific, cytotoxic T lymphocyte precursors in either the lymph node or the lung. Substantial involvement of CD4+ T cells is not essential for the development of effective cell-mediated immunity in mice with influenza.

Animals↗
PubMed1990

Dissection of an inflammatory process induced by CD8+ T cells.

A massive delayed type hypersensitivity (DTH) reaction occurs in the cerebrospinal fluid (CSF) of mice with lymphocytic choriomeningitis (LCM). In this article, Peter Doherty and colleagues analyze this reaction together with the population dynamics of the regional lymph node to give a comprehensive picture of the events underlying this CD8+ T-cell-mediated immunopathological disease. Their findings are of general relevance to the understanding of inflammation.

Animals↗
PubMed1990

Binding of monoclonal antibodies and T cell effector function in vivo.

The capacity of adoptively transferred CD8+ effector T cells to induce meningitis in immunosuppressed, or unsuppressed, recipients infected with lymphocytic choriomeningitis virus (LCMV) may be diminished by prior incubation of the lymphocytes with IgM monoclonal antibodies (MAbs) specific for CD8 or Thy1.2. The same is true, though to a lesser extent, for the further proliferation of donor T cells in the spleens of the immunosuppressed mice. This inhibition of cell mediated immunity can be overcome, at least for the unsuppressed recipients, by increasing the numbers of cells that are transferred, even though exposure to Mab+ complement abrogates all cytotoxic T cell activity in vitro. The LCM model thus provides a quantitative system for assessing the consequences of MAb binding for T cell trafficking and effector function in vivo.

Animals↗
PubMed1979

Patterns of virus-immune T-cell responsiveness. Comparison of (H-2k X H-2b) leads to H-2b radiation chimeras and negatively selected H-2b lymphocytes.

Negatively selected H-2K(b)D(b) TDL can be induced to respond strongly to vaccinia virus presented in the context of both H-2K(k) and H-2D(b) when stimulated in irradiated H-2K(k)D(b) recipients. Addition of excess (H- 2K(k)D(b) x H-2K(b)D(b))F1 TDL, which are low responders to H-2D(b)-vaccinia virus, does not obviously suppress the reactivity pattern of the H-2K(b)D(b) T cells. However, lymphocytes from chimeras made by reconstituting H- 2K(b)D(b) mice with (H-2K(k)D(k) x H-2K(b)D(b))F(l) bone marrow cells make little, if any, cytotoxic T-cell response to vaccinia virus when sensitized in H-2K(k)D(b) recipients. We have thus documented one instance where the responder phenotype of T ceils from an F(l) {arrow} parent chimera is not equivalent to that associated with the H-2 type of the parental thymus. Lymphocytes from both the chimera and the H-2K(b)D(b) parent (after negative selection) are tolerant to the H-2K(k) and I-A(k) alloantigens encountered in the recipient, but the chimera T cells are also defective in their response to a neoantigen (vaccinia virus) presented in the context of H-2K(k) which the parental T cells invariably recognize. It is thus possible that at least part of the phenomenology associated with the F(l) {arrow} parent radiation chimeras reflects deletion of repertoire in the context of H-2 antigens present during thymocyte ontogeny on other than radiation-resistant thymic epithelium.

Animals↗